The invention discloses a 
silicon carbide Trench MOS device and a manufacturing method thereof, and belongs to the technical field of power semiconductors. The method includes: a layer of a polysilicon region distributed in a pi shape is additionally arranged under a 
trench gate structure of a conventional device, the polysilicon region and an epitaxial layer form a Si / SiC 
heterojunction, and a 
diode is integrated in the device. Compared with a parasitic 
silicon carbide diode which directly employs a 
silicon carbide Trench MOS, according to the 
silicon carbide Trench MOS device and the manufacturing method thereof, the junction 
voltage drop of the device 
diode during application is substantially reduced, and the switch-on characteristic of the device is improved through large 
junction area of the 
heterojunction; moreover, the gate-drain 
capacitance and the ratio of the gate-drain 
capacitance to the gate-source 
capacitance of the device are reduced, and the performance and the reliability of the device MOS during application are enhanced; besides, the 
silicon carbide Trench MOS device and the manufacturing method thereof are also advantageous in that the 
reverse recovery time is short, the 
reverse recovery charges are less, and advantages including low reverse leakage, high 
breakdown voltage, and good temperature stabilization performance of the conventional 
silicon carbide Trench MOS device are maintained. In conclusion, according to the silicon carbide Trench MOS device and the manufacturing method thereof, the prospect is wide in circuits such as inversion circuits and 
chopper circuits etc.